Methods and apparatus for selective oxidation of a substrate

ABSTRACT

Methods and apparatus for improving selective oxidation against metals in a process chamber are provided herein. In some embodiments, a method of oxidizing a first surface of a substrate disposed in a process chamber having a processing volume defined by one or more chamber walls may include exposing the substrate to an oxidizing gas to oxidize the first surface; and actively heating at least one of the one or more chamber walls to increase a temperature of the one or more chamber walls to a first temperature of at least the dew point of water while exposing the substrate to the oxidizing gas.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional patent applicationSer. No. 61/597,900, filed Feb. 13, 2012, which is herein incorporatedby reference.

FIELD

Embodiments of the present invention generally relate to substrateprocessing.

BACKGROUND

In the manufacture of semiconductor devices, selective oxidation is usedto target certain materials, such as silicon and oxides of silicon,while avoiding oxidation of other materials such as metals. Rapidthermal processing (RTP) is also used in the manufacture ofsemiconductor devices to change the characteristics of a deposited filmor crystal lattice and generally includes processes such as annealing,silicidation, and oxidation of a substrate surface. The inventors havediscovered that selective oxidation processes against metals in an RTPprocess using hydrogen and oxygen can undesirably result in theformation of moisture or condensation within the RTP chamber. Theinventors have further observed that such moisture can act to transportcontaminant particles onto the semiconductor wafer within the processchamber and further may result in undesirable oxidation of the metals onthe substrate.

Accordingly, the inventors have provided improved methods and apparatusfor selective oxidation against metals.

SUMMARY

Methods and apparatus for improving selective oxidation against metalsin a process chamber are provided herein. In some embodiments, a methodof oxidizing a first surface of a substrate disposed in a processchamber having a processing volume defined by one or more chamber wallsmay include exposing the substrate to an oxidizing gas to oxidize thefirst surface; and actively heating at least one of the one or morechamber walls to increase a temperature of the one or more chamber wallsto a first temperature of at least the dew point of water while exposingthe substrate to the oxidizing gas.

In some embodiments, a method of oxidizing a first surface of asubstrate disposed in a process chamber having a processing volumedefined by one or more chamber walls may include exposing the one ormore chamber walls to a first gas comprising at least one of hydrogen(H₂), nitrogen (N₂), or an inert gas while raising the temperature ofthe one or more chamber walls to a first temperature greater than thedew point of water; exposing the substrate to an oxidizing gas toselectively oxidize the first surface for a first period of timebeginning when or after the one or more chamber walls reaches the firsttemperature, wherein the one or more chamber walls increases intemperature from the first temperature to a second temperature duringthe first period of time and wherein the one or more chamber wallsremains above the first temperature for the remainder of the firstperiod of time; ceasing flow of the oxidizing gas after the first periodof time; and subsequently exposing the one or more chamber walls to asecond gas comprising nitrogen (N₂) while raising the temperature of theone or more chamber walls to a third temperature greater than the secondtemperature.

In some embodiments, an apparatus for thermally processing a substratemay include a chamber having sidewalls defining a processing volume andhaving a substrate support disposed within the processing volume; afirst heat source comprising a plurality of lamps disposed opposite thesubstrate support to provide thermal energy to a substrate when disposedon the substrate support, wherein the energy density of the plurality oflamps is about 30 watts per square centimeter to about 80 watts persquare centimeter; and a second heat source coupled to the sidewalls toprovide thermal energy to the sidewalls.

Other and further embodiments of the present invention are describedbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention, briefly summarized above anddiscussed in greater detail below, can be understood by reference to theillustrative embodiments of the invention depicted in the appendeddrawings. It is to be noted, however, that the appended drawingsillustrate only typical embodiments of this invention and are thereforenot to be considered limiting of its scope, for the invention may admitto other equally effective embodiments.

FIG. 1 depicts a flow chart of a method for oxidizing a substrate in aprocess chamber in accordance with some embodiments of the presentinvention.

FIG. 2 depicts a flow chart of a method for oxidizing a substrate in aprocess chamber in accordance with some embodiments of the presentinvention.

FIG. 3 depicts a schematic sectional side view of a thermal reactorsuitable for use in accordance with some embodiments of the invention.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. The figures are not drawn to scale and may be simplifiedfor clarity. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

Methods and apparatus for improving selective oxidation against metalsin a process chamber are provided herein. FIG. 1 depicts a flowchart ofa method 100 of selectively oxidizing a first surface of a substratedisposed in a process chamber having a processing volume defined by oneor more chamber walls in accordance with some embodiments of the presentinvention. Although described herein in connection with selectiveoxidation processes, the inventive methods and apparatus may be usefulin non-selective oxidation processes or other processes where thesuppression of moisture within the process chamber may be desired.

Selective oxidation (e.g., oxidation of portions of a structure ordevice on a substrate) requirements may arise when oxidation processesneed to be carried out in the presence of exposed metal or metal alloys.In such cases, the oxidation process needs to be carried out withoutabnormal oxidation of the exposed metal/metal alloy. The need forselective oxidation in the case of Logic, DRAM, Flash devices, or thelike, typically arises during gate sidewall re-oxidation processes aftera gate stack etch when metal gate electrodes are present, such as gateelectrodes comprising titanium (Ti), titanium nitride (TiN), tungsten(W), tungsten silicide nitride (WSixN), tungsten nitride (WN), tantalumcarbide (TaC), tantalum nitride (TaN), or the like. The methods andapparatus described herein may also be used, however, in other processeswhere selective oxidation is desired.

The process chamber may be any type of process chamber configured toperform a selective oxidation process, as modified by the teachingsprovided herein. Examples of process chambers suitable for modificationinclude any of the RADIANCE®, RADIANCE® PLUS, or VANTAGE® processchambers, or any other process chamber capable of performing a thermalprocess, for example a rapid thermal process (RTP), all available fromApplied Materials, Inc., of Santa Clara, Calif. Other suitable processchambers, including those available from other manufacturers may also bemodified and used in accordance with the teachings provided herein. Insome embodiments, the process chamber may be similar to the processchamber described below with respect to FIG. 3.

The method 100 generally begins at 102, by exposing a first surface of asubstrate to an oxidizing gas to oxidize the first surface of thesubstrate. The first surface is a non-metal containing layer atop asubstrate which may comprise a material such as crystalline silicon(e.g., Si<100> or Si<111>), silicon oxide, strained silicon, silicongermanium, doped or undoped polysilicon, doped or undoped siliconwafers, patterned or non-patterned wafers, silicon on insulator (SOI),carbon doped silicon oxides, silicon nitride, doped silicon, germanium,gallium arsenide, glass, sapphire, or the like. In some embodiments, theoxidation process may be a selective oxidation process, wherein thesubstrate further comprises an exposed metal surface. For example, insome embodiments, the first surface of the substrate may be non-metallicand the substrate may further comprise an exposed second surface that ismetallic, and the first and second surfaces may be exposed to theoxidizing gas to oxidize the first surface, while substantially notoxidizing the exposed second surface.

In some embodiments, the oxidation process may utilize an oxidizing gascomprising oxygen (O₂), nitrous oxide (N₂O), nitric oxide (NO), orcombinations thereof. In some embodiments, the oxidizing gas may furtherinclude an additional gas comprising hydrogen (H₂). In some embodiments,the oxidizing gas may further include a first gas comprising hydrogen(H₂) and at least one of nitrogen (N₂), ammonia (NH₃), or an inert gas.In some embodiments, the oxidizing gas comprises oxygen (O₂) andhydrogen (H₂). In some embodiments, the oxidizing gas may comprise atleast 85% hydrogen (H₂) with the balance being predominantly, orsubstantially only, oxygen (O₂). The oxidizing gas may be flowed at anysuitable flow rate depending upon, for example, one or more of thesubstrate/chamber size, the materials of the substrate, the oxidizinggas composition, or the like. In some embodiments, the oxidizing gas maybe provided at a total flow rate in the range of about 10,000 to about20,000 sccm. In some embodiments, the oxidizing gas is provided whilemaintaining the process chamber at a pressure of about 450 to about 530Torr, although higher and lower pressures may be provided.

The inventors have discovered that oxidation processes using hydrogenand oxygen may undesirably produce moisture within the process chamber.The moisture may undesirably transport contaminant particles onto thesurface of the substrate and may also undesirably oxidize metalcomponents of the substrate. Without wishing to be bound by theory, theinventors believe that this problem may be a result of a temperature ofthe walls of the chamber being below the dew point for water in theprocessing volume of the process chamber. The inventors have observedthat even though the chamber walls in conventional oxidation chambersmay be passively heated during the oxidation process, the chamber wallsdo not get heated to a sufficient temperature or do not heat up at asufficiently rapid rate sufficient to eliminate or reduce moistureformation within the process chamber. For example, in a process chamberhaving a lamp assembly positioned above the substrate to supply heat tothe substrate, it may also indirectly heat the chamber walls, and/orheat radiating from the substrate may heat the chamber walls. However,the inventors have observed that this indirect, or passive, heating doesnot adequately increase the temperature of the chamber walls to a levelthat would inhibit moisture formation within the process chamber.

The inventors have discovered that actively heating the chamber walls toa temperature at least equal to the dew point of water, moistureformation within the process chamber may be advantageously inhibited.Moreover, the inventors have discovered that minimizing the formation ofmoisture within the process chamber further advantageously reducescontaminant particles on the substrate, including undesired oxidation ofmetal on the substrate. Therefore, at 104, at least one of the chamberwalls are actively heated to increase the temperature of the chamberwalls to at least the dew point of water while exposing the substrate tothe oxidizing gas.

As used herein, active heating, or actively heating, means the directapplication of heat or energy to raise the temperature of the walls ofthe process chamber via a heating apparatus disposed within or coupledto the chamber walls, such as a heat exchanger or a heat jacket, whichsurrounds and heats the chamber walls, for example using a heat transfermedium, resistive heaters, radiative heat lamps, or the like. Activelyheating the chamber walls advantageously facilitates raising thetemperature of the chamber walls to the dew point faster than throughthe indirect heating described above. Active heating of the chamberwalls may also provide a more repeatable chamber wall temperature beforethe process step, as compared to relying upon passive methods to heatthe walls, because the active heating of the chamber walls can bewell-controlled. For example, in some embodiments, a sensor (e.g., 312)such as a thermocouple or other suitable sensor may be provided toindicate the temperature of the chamber wall. The sensor may providedata corresponding directly to the temperature of inner surfaces of thechamber wall, or the sensor may provide data corresponding to thetemperature of an outer surface of the chamber wall, from which theinner chamber wall temperature may be determined. The temperature datafrom the sensor may be provided to a controller (e.g., 302) tofacilitate control over the active heating of the chamber walls (e.g.,configured in a feedback loop).

The flow of the oxidizing gas may continue for a desired period of timeuntil the process is completed. Upon completion of the oxidationprocess, the flow of the oxidizing gas to the substrate is ceased, asdepicted at 106, and the substrate may be further processed as desired.

Optionally, in some embodiments, the process chamber may be exposed to afirst gas comprising at least one of hydrogen, nitrogen, or an inertgas, such as argon, prior to exposing the substrate to the oxidizinggas. In some embodiments, the first gas is hydrogen (H₂). For example,in some embodiments, the oxidation gas may be a mixture of oxygen (O₂)and hydrogen (H₂) and the hydrogen (H₂) may be provided initially as thefirst gas, with the oxygen (O₂) subsequently being introduced to startthe flow of the oxidation gas mixture.

In some embodiments, the first gas is introduced to the process chamberwhile heating the substrate, for example by irradiating the substratewith energy from heating lamps. In some embodiments, the energy providedto the substrate is about equal to the energy provided during theoxidation process. In some embodiments, the energy provided to thesubstrate is sufficient for a pyrometer (e.g., 318) aimed at a backsideof the substrate to read a temperature of about 700 to about 1000degrees Celsius. Providing the first gas while providing heat energy mayfacilitate more rapidly raising the temperature of the chamber walls toa first temperature of about 5 to about 10 degrees Celsius above the dewpoint temperature. The inventors have observed that providing the firstgas while providing heat energy further advantageously facilitatesheating portions of the chamber that are typically protected frompassive heating, such as slit valve openings or other components thatmay be shielded or more remotely disposed with respect to the processheat source and/or the substrate, thereby further reducing moistureformation on such components. In some embodiments, the chamber walls maysimultaneously be actively heated while the first gas is provided. Insome embodiments, the process chamber is exposed to the first gas forabout 15 seconds while the substrate is heated, although other periodsof time may be used. In some embodiments, the first gas is provided at aflow rate range of about 10 to about 20 slm. The inventors havediscovered that providing the first gas while providing heat energy incombination with actively heating the chamber walls furtheradvantageously improves the selectivity of the oxidation process againstmetal.

Other variations of the inventive methods may also be used. For example,FIG. 2 depicts a flowchart of a method 200 of selectively oxidizing afirst surface of a substrate disposed in a process chamber having aprocessing volume defined by one or more chamber walls in accordancewith some embodiments of the present invention. Details regarding thefirst surface of the substrate, the substrate and the process chamberhave been provided above with respect to FIG. 1.

The method 200 begins at 202, by exposing the chamber walls of a processchamber to a first gas comprising at least one of hydrogen, nitrogen, oran inert gas, such as argon. The first gas is introduced to the processchamber while heating the substrate such that a pyrometer aimed at abackside of the substrate will read a temperature of about 700 to about1000 degrees Celsius. Providing the first gas while heating thesubstrate may be performed for a sufficient time period in order toraise the temperature of the chamber walls to a first temperature ofabout 5 to about 10 degrees Celsius above the dew point temperature.

Next, at 204, the substrate is exposed to an oxidizing gas toselectively oxidize the first surface of the substrate for a firstperiod of time. The oxidizing gas may be any oxidizing gas as discussedabove with respect to FIG. 1. The first period of time begins when thechamber walls reach the first temperature. During the first period oftime, the chamber walls increase from the first temperature to a secondtemperature. The temperature of the chamber walls remains above thefirst temperature during the remainder of the first period of time. Thefirst period of time ends once the selective oxidation process iscompleted.

Next, at 206, the flow of oxidizing gas to the process chamber is ceasedafter the first period of time and, at 208, the chamber walls may besubsequently exposed to a second gas comprising one or more of nitrogen(N₂), an inert gas, or hydrogen (H₂). In some embodiments, the secondgas is nitrogen (N₂). The second gas is introduced while raising thetemperature of the chamber walls to a third temperature, greater thanthe second temperature. For example, the temperature of the chamberwalls may be raised by providing heat to the processing volume of theprocess chamber, for example, using lamps directed toward the substrate.The lamps may be the lamps used to provide heat to the substrate duringthe oxidation process and may be sufficient, for example, to heat thesubstrate to so that a pyrometer aimed at a backside of the substratereads a temperature of about 700 to about 1000 degrees Celsius. Theinventors have discovered that providing the above-describedpost-oxidation exposure to the second gas and continuing to heat thechamber walls further reduces moisture formation on the chamber wallsand further reduces particles on the substrate. In addition, theinventors have discovered that providing the above-describedpost-oxidation exposure to the second gas and continuing to heat thechamber walls further improves the selectivity of the oxidation processagainst metals.

FIG. 3 depicts a schematic sectional side view of a thermal reactor foruse in accordance with some embodiments of the invention. The thermalprocessing chamber 300 generally comprises a lamp assembly 310, achamber assembly 330 defining a processing volume 339, and a substratesupport 338 disposed in the processing volume 339.

The lamp assembly 310 (e.g., a first heat source) is positioned abovethe chamber assembly 330 and is configured to supply heat to theprocessing volume 339 via a quartz window 314 disposed on the chamberassembly 330. The lamp assembly 310 is configured to house a processheating source, such as a plurality of tungsten-halogen lamps forproviding a tailored infrared heating means to a substrate 301 disposedon the substrate support 338. In some embodiments, the plurality oflamps have an energy density of about 30 watts per square centimeter toabout 80 watts per square centimeter. One or more pyrometers (onepyrometer 318 shown) may be disposed beneath the substrate 301 and aimedat a backside of the substrate 301 to provide data corresponding to thetemperature of the substrate. The data from the one or more pyrometersmay be provided to a controller (e.g., 302) to facilitate feedbackcontrol over the process heating source and for use in facilitating themethods described herein.

The chamber assembly 330 generally comprises a base ring 340 having oneor more chamber walls defining the processing volume 339 with the quartzwindow 314 and a bottom wall 316. Although the term ring is used herein,the base ring 340 need not be circular and other shapes are contemplatedas well. The base ring 340 may have an inlet 331 coupled to a gas source335 to provide one or more process gases to the processing volume 339(such as the oxidizing gas, the first gas, and/or the second gasdiscussed above). An outlet 334, disposed on an opposite side of thebase ring 340 from the inlet 331, is coupled to an exhaust assembly 324which is in fluid communication with a pump system 336. The exhaustassembly 324 defines an exhaust volume 325, which is in fluidcommunication with the processing volume 339 via the outlet 334. Theexhaust volume 325 is designed to allow uniform gas flow distributionacross the processing volume 339.

In some embodiments, a heating apparatus may be provided at leastpartially disposed within or coupled to the chamber walls (e.g., asecond heat source). For example, in some embodiments, a first heatexchanger 355 is coupled to the base ring 340 to control the temperatureof the chamber walls by circulating a heat exchange fluid through one ormore conduits 326 disposed in the base ring 340. In some embodiments,the first heat exchanger 355 is set to at least 60 degrees Celsius.Alternatively or in combination, a heat jacket 328 may be thermallycoupled to the base ring 340 to provide heat to the chamber walls, forexample, by flowing a heat transfer fluid through the heat jacket 328,by providing heater elements, such as resistive heaters or heat lamps,within the heat jacket 328, or the like.

In some embodiments, a second heat exchanger 356 is coupled to the lampassembly 310 to allow heat exchange fluid to be circulated to the lampassembly 310 through an inlet 309 to keep the lamp assembly 310 coolduring processing. In some embodiments, the first heat exchanger and thesecond heat exchanger may be maintained at different temperatures. Insome embodiments, the second heat exchanger 356 may also be coupled tothe bottom wall 316, as indicated by dashed line 322. Alternatively, insome embodiments, the first heat exchanger 355 may also be coupled tothe bottom wall 316, as indicated by dashed line 320.

A thermocouple 312, or other suitable sensor, may be coupled to the basering 340 to monitor the outer chamber wall temperature and to determinethe inner chamber wall temperature. The thermocouple 312 may be part of,or coupled to, a system controller, such as the system controller 302that may control the operations of the thermal processing chamber 300.

To facilitate control of the process chamber 300 as described above, acontroller 302 comprises a central processing unit (CPU) 304, a memory306, and support circuits 308 for the CPU 304 and facilitates control ofthe components of the chamber 300. The controller 302 may be one of anyform of general-purpose computer processor that can be used in anindustrial setting for controlling various chambers and sub-processors.The memory 306, or computer-readable medium, of the CPU 304 may be oneor more of readily available memory such as random access memory (RAM),read only memory (ROM), floppy disk, hard disk, or any other form ofdigital storage, local or remote. The support circuits 308 are coupledto the CPU 304 for supporting the processor in a conventional manner.These circuits include cache, power supplies, clock circuits,input/output circuitry and subsystems, and the like. The methodsperformed in the process chamber 300, or at least portions thereof, maybe stored in the memory 306 as a software routine. The software routinemay also be stored and/or executed by a second CPU (not shown) that isremotely located from the hardware being controlled by the CPU 304.

Thus, methods and apparatus for improving selectivity against metalshave been provided herein. The inventive methods and apparatus mayadvantageously provide improve selective oxidation against metals andminimize the transport of contaminants to the substrate via condensationformed in the process chamber.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof.

1. A method of oxidizing a first surface of a substrate disposed in aprocess chamber having a processing volume defined by one or morechamber walls, the method comprising: exposing the substrate to anoxidizing gas to oxidize the first surface; and actively heating atleast one of the one or more chamber walls to increase a temperature ofthe one or more chamber walls to a first temperature of at least the dewpoint of water while exposing the substrate to the oxidizing gas.
 2. Themethod of claim 1, wherein exposing the substrate to the oxidizing gasto oxidize the first surface further comprises heating and reacting amixture of hydrogen (H₂) and oxygen (O₂) within the processing volume.3. The method of claim 1, further comprising: exposing the one or morechamber walls to a first gas comprising at least one of hydrogen (H₂),nitrogen (N₂), or an inert gas while raising the temperature of the oneor more chamber walls to the first temperature, wherein the firsttemperature is about 5 to about 10 degrees Celsius above the dew point.4. The method of claim 3, further comprising: heating the substrate toread a temperature with a pyrometer aimed at a backside of the substrateof about 700 to about 1000 degrees Celsius while raising the temperatureof the one or more chamber walls to the first temperature.
 5. The methodof claim 1, wherein exposing the substrate to the oxidizing gas tooxidize the first surface further comprises: in combination with theoxidizing gas, exposing the substrate to an additional gas comprisinghydrogen (H₂) or hydrogen (H₂) in combination with at least one ofnitrogen (N₂), ammonia (NH₃), or an inert gas.
 6. The method of claim 5,wherein the additional gas is provided at a flow rate ratio relative tothe oxidizing gas of greater than about 4:1.
 7. The method of claim 5,wherein the first surface of the substrate is non-metallic and whereinthe substrate further comprises an exposed second surface that ismetallic, and wherein exposing the substrate to the oxidizing gas tooxidize the first surface further comprises substantially not oxidizingthe exposed second surface.
 8. The method of claim 1, furthercomprising: ceasing the flow of the oxidizing gas after oxidizing thefirst surface; and subsequently raising the temperature of the one ormore chamber walls to a second temperature greater than the firsttemperature.
 9. The method of claim 8, further comprising: exposing theone or more chamber walls to a second gas comprising nitrogen (N₂) whileraising the temperature of the one or more chamber walls to the secondtemperature.
 10. The method of claim 9, further comprising: heating thesubstrate to read a temperature with a pyrometer aimed at a backside ofthe substrate of about 700 to about 1000 degrees Celsius to passivelyraise the temperature of the one or more chamber walls to the secondtemperature.
 11. The method of claim 1, further comprising:independently controlling a temperature of a bottom wall of the processchamber disposed below the one or more chamber walls that are activelyheated.
 12. A method of oxidizing a first surface of a substratedisposed in a process chamber having a processing volume defined by oneor more chamber walls, comprising: exposing the one or more chamberwalls to a first gas comprising at least one of hydrogen (H₂), nitrogen(N₂), or an inert gas while raising the temperature of the one or morechamber walls to a first temperature greater than the dew point ofwater; exposing the substrate to an oxidizing gas to selectively oxidizethe first surface for a first period of time beginning when or after theone or more chamber walls reaches the first temperature, wherein the oneor more chamber walls increases in temperature from the firsttemperature to a second temperature during the first period of time andwherein the one or more chamber walls remains above the firsttemperature for the remainder of the first period of time; ceasing flowof the oxidizing gas after the first period of time; and subsequentlyexposing the one or more chamber walls to a second gas comprisingnitrogen (N₂) while raising the temperature of the one or more chamberwalls to a third temperature greater than the second temperature. 13.The method of claim 12, wherein exposing the substrate to the oxidizinggas to selectively oxidize the first surface further comprises: exposingthe substrate to hydrogen (H₂) and, optionally, at least one of nitrogen(N₂), ammonia (NH₃), or an inert gas in combination with the oxidizinggas, wherein the hydrogen (H₂) and, optionally, at least one of nitrogen(N₂), ammonia (NH₃), or the inert gas is provided at a flow rate ratioof at least about 4:1 with respect to the oxidizing gas.
 14. Anapparatus for thermally processing a substrate, comprising: a chamberhaving sidewalls defining a processing volume and having a substratesupport disposed within the processing volume; a first heat sourcecomprising a plurality of lamps disposed opposite the substrate supportto provide thermal energy to a substrate when disposed on the substratesupport, wherein the energy density of the plurality of lamps is about30 watts per square centimeter to about 80 watts per square centimeter;and a second heat source coupled to at least one of the sidewalls toprovide thermal energy to the sidewalls.
 15. The apparatus of claim 14,wherein the second heat source comprises a heat exchange loop having aconduit for flowing a heat exchange medium through the sidewalls orthrough a body disposed adjacent to the sidewalls.
 16. The apparatus ofclaim 14, wherein the second heat source comprises one or more resistiveheaters disposed in or adjacent to the sidewalls.
 17. The apparatus ofclaim 14, further comprising: a heat exchange loop having conduitspassing adjacent to the lamps to remove heat from components of theprocess chamber adjacent to the lamps.
 18. The apparatus of claim 14,further comprising: a heat exchange loop having conduits passing throughor adjacent to a lower portion of the chamber disposed beneath thesubstrate support to control a temperature of the lower portion of thechamber independently of the sidewalls that are coupled to the secondheart source.
 19. The apparatus of claim 14, wherein the chamber furthercomprises: a base ring including the sidewalls and defining theprocessing volume to be a cylindrical center processing volume; a topwall coupled to the base ring to seal the cylindrical center processingvolume from an upper end of the base ring; and a bottom wall coupled tothe base ring to seal the cylindrical center volume from a lower end ofthe sidewalls of the base ring, wherein the first heat source isdisposed above the top wall, and wherein the second heat source iscoupled to the base ring.
 20. The apparatus of claim 19, furthercomprising one or more sensors coupled to the base ring to monitor thetemperature of the sidewalls.